1. Field of the Invention
The present invention relates to a disk player, more precisely relates to a disk player having a motor for rotating a disk and an optical pick-up being capable of moving in the radial direction of a disk driven by the motor for reading recorded data.
2. Description of Background Art
In conventional data recording disks, e.g., CD-ROM, CD-I, data are recorded in the manner of CLV (Constant Linear Velocity). Therefore, in conventional disk players, a motor is feed back controlled so as to coincide frequency and phase of bit signals of output-data elements, which are read from a disk driven by a motor, with frequency and phase of master clock signals, which have fixed frequency for sampling the output-data elements. The rotational speed of the disk must be changed on the basis of positions of an optical pick-up so as to fix linear speed between the disk and the optical pick-up. Namely, with the movement of the optical pick-up from an edge to a center of the disk, the rotational speed of the disk must be gradually accelerated.
However, above described conventional disk player has the following disadvantages.
In the conventional disk player, the motor speed is feed back controlled with the movement of the optical pick-up. And the output-data elements are sampled after the motor speed reaches an object speed. Generally, it takes a longer time to provide a feed back control to mechanical systems, e.g., motors. Thus, it also takes a longer time to read the output-data elements from a disk.
In addition, the motor speed is always changed by controlling current density with the movement of the optical pick-up. Thus, the motor is accelerated and braked many times, so that electric power consumption is increased and durability of the motor is decreased.